Question

For a cell, the cell reaction is : $Mg(s)+C{u}^{2+}(aq)\to Cu(s)+M{g}^{2+}(aq)$ If the standard reduction potentials of Mg and Cu are -2.37 and +0.34 V respectively, the emf of the cell is

• A. 2.03V
• B. -2.03V
• C. 2.7 IV
• D. -2.71 V

Answer 1

Answer: (C)

Cell reaction, $Mg(s)+C{u}^{2+}(aq.)\to Cu(s)+M{g}^{2+}(aq.).$
In this equation Mg is oxidised and Cu is reduced. So, oxidation takes place at Mg electrode and reduction takes place at Cu electrode. EMF Of Cell
$=E_{cathode}-E_{anode}$
$=E_{reduction}-E_{oxidation}$
$=0.34-(-2.37)$ $=0.34+2.37=2.71V$